Obama Poised to Claim Victory

Barack Obama is poised to claim the Democratic presidential nomination this week, but Hillary Clinton shows no signs of conceding. How their endgame plays out -- in continued rivalry, as running mates or something in between -- will go a long way toward determining Democrats' fortunes this fall.

With more Democratic Party leaders -- the so-called superdelegates -- set to endorse Sen. Obama in coming days, and the dispute over Michigan...